The invention relates to electrical signal generators for generating signals at specific frequencies.
Electrical signal generators are widely used in the electrical and electronics industry for generating electrical signals at various frequencies, mainly for the purposes of testing telecommunications and other equipment. In its basic form, such a signal generator in the prior art may comprise an adjustable frequency source, which may for example be an adjustable oscillator or an adjustable frequency synthesizing system, together with a control by which an operator can adjust the frequency. In addition, such a signal generator may have some form of indicator to indicate the actual frequency of the generated signal. Such an indicator may, for example, be driven from a counter which counts the frequency of the generated signal. Therefore, to cause a required change in generated frequency, the operator operates the control until the indicator indicates the new frequency.
Such signal generators find very wide use in industry. However, in certain applications they are not entirely satisfactory because it is time-consuming for an operator to reset such a signal generator to a new, desired, frequency, and, in testing telecommunications equipment for example, it may be necessary for the operator to repeatedly have to reset the generated frequency to different values in order to test the equipment throughout its operating ranges.
It is therefore an object of the invention to provide an improved electrical signal generator.
A more specific object of the invention is to provide an electrical signal generator having an improved facility for adjusting its output frequency.